<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>结构性伪类选择器使用</title>
		<style type="text/css">
			/*匹配html元素*/
			:root{
				background: #fcfcc0;
			}
			/*匹配到第一个div*/
			div:empty{
				height: 20px;
				background: red;
			}
			:not(div){
				color: blueviolet;
			}
			
		</style>
	</head>
	<body>
		<div></div>
		<div></div>
		<p>我是段落</p>
	</body>
</html>
